The present invention relates to novel fluorosilicone block copolymers and to a method for their preparation. More specifically, the present invention relates to fluorosilicone block copolymers that are composed of poly(perfluoroalkylmethylsiloxane) and polydimethylsiloxane chains and also to a method for the preparation of these fluorosilicone block copolymers.
Japanese Patent Publication (Kokoku) Number Sho 55-50056 (50,056/1980) discloses a polyorganosiloxane copolymer that is prepared by the polymerization of siloxane cyclics (Me.sub.2 Si O).sub.X with the cyclic trisiloxane (CF.sub.3 C.sub.2 H.sub.4 SiMeO).sub.3 in the presence of potassium hydroxide; however, this polyorganosiloxane copolymer is a random copolymer. In addition, Japanese Patent Application Laid Open (Kokai) Number Sho 51-134796 (134,796/1976) discloses a method in which a mixture of the cyclic trisiloxane (CF.sub.3 C.sub.2 H.sub.4 SiMeO).sub.3 and the cyclic trisiloxane (Me.sub.2 SiO).sub.X is copolymerized using alkyllithium catalyst. But here again, this method still does not afford an AB nor an ABA fluorosilicone block copolymer (A=poly(perfluoroalkylmethylsiloxane) chain, B=polydimethylsiloxane chain).
The present invention takes as its objects the introduction of novel AB and ABA fluorosilicone block copolymers in which A is a poly(perfluoroalkylmethylsiloxane) chain and B is a polydimethylsiloxane chain as well as the introduction of a method for the synthesis of these novel fluorosilicone block copolymers. A further object of the present invention is the introduction of a method for the preparation of fluorosilicone block copolymer whereby the fluorosilicone block copolymer is obtained by a one-pot synthesis from cyclic trisiloxanes.
The fluorosilicone block copolymers of the present invention as described herein are novel polymers with an AB or ABA fluorosilicone block copolymer structure in which A is the poly(perfluoroalkylmethylsiloxane) chain and B is the polydimethylsiloxane chain. These novel polymers are useful as compatibilizers for silicone rubber blends. For example, they are useful as compatibilizers in the preparation of dimethylsilicone rubber/fluorosilicone rubber mixtures, dimethylsilicone rubber/fluororubber mixtures, and fluorosilicone rubber/fluororubber mixtures.